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MEDICINE MONOGRAPH CODE: [11.14] ID: TIP-MED-000218 ⚠️ HIGH-ALERT / SPECIALIST SUPERVISION

Phenobarbitone (Phenobarbital) & Clobazam

Active Ingredient / Scientific Identity: Phenobarbitone • Class: Barbiturate & 1,5-Benzodiazepine Antiepileptics (GABA-A Allosteric Modulators)

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THE INDIAN PHARMACIST — Educational Reference Sheet
Profile: Phenobarbitone (Phenobarbital) & Clobazam ([11.14] | ID: TIP-MED-000218) • Last Reviewed: 2026-11-10
Source URL: https://theindianpharmacist.com/medicine/11-14-phenobarbitone-phenobarbital-clobazam/
Generic / Entity NamePhenobarbitone (Phenobarbital) & Clobazam ([11.14])
Verified Indian Brands / RefGeneric Compendial Entry (No Commercial Brand Claimed)
Pharmacological ClassBarbiturate & 1,5-Benzodiazepine Antiepileptics (GABA-A Allosteric Modulators)
Available Dosage FormsPhenobarbitone Tablets: 30 mg, 60 mg; Paediatric Syrup: 20 mg/5 mL; IV/IM Injection: 200 mg/mL. Clobazam Score
Regulatory ClassificationSchedule H1 Prescription Drug (Mandatory Red-Bordered Rx Warning & 3-Year Register un
Key Warning & Review DateRenal: Extend Phenobarbitone interval if eGFR <10 mL/min. Hepatic: Contraindicated in marked hepatic encephalopathy; halve
Reviewed: 2026-11-10
Safety Matrix:⚖️ Legal Status: Schedule H1 Prescription Drug (Mandatory Red-Bordere🚨 Clinically High-Alert: Independent Dose & Route Verification Required

1. Clinical & Scientific Overview

Phenobarbitone (Phenobarbital) & Clobazam (TIP-MED-000218, Reference Code [11.14]) is classified under Neurology & Antiepileptic Medicines (Ch 11) as a Barbiturate & 1,5-Benzodiazepine Antiepileptics (GABA-A Allosteric Modulators). Within the Indian regulatory and compendial framework, it is governed under Schedule H1 Prescription Drug (Mandatory Red-Bordered Rx Warning & 3-Year Register under Rule 65 of Drugs Rules 1945).

Verified Indian Market Examples / Compendial Status:
Representative Indian Market Examples (Edition 2.7 Ch 11 [11.14], p. 146): Gardenal (Abbott — 30 mg, 60 mg), Luminal, Beetal (30 mg, 60 mg, 20 mg/5mL Syrup, 200 mg/mL Inj); Clobazam: Frisium (Sanofi), Cloba (Intas — 5 mg, 10 mg, 20 mg), Lobazam (Sun) — Strengths & Dosage Forms: Phenobarbitone Tablets: 30 mg, 60 mg; Paediatric Syrup: 20 mg/5 mL; IV/IM Injection: 200 mg/mL. Clobazam Scored Tablets: 5 mg, 10 mg, 20 mg.
Representative Indian Market Examples (Edition 2.7 Ch 11 [11.14], p. 146): Gardenal (Abbott — 30 mg, 60 mg), Luminal, Beetal (30 mg, 60 mg, 20 mg/5mL Syrup, 200 mg/mL Inj); Clobazam: Frisium (Sanofi), Cloba (Intas — 5 mg, 10 mg, 20 mg), Lobazam (Sun) — Strengths & Dosage Forms: Phenobarbitone Tablets: 30 mg, 60 mg; Paediatric Syrup: 20 mg/5 mL; IV/IM Injection: 200 mg/mL. Clobazam Scored Tablets: 5 mg, 10 mg, 20 mg.
Dosage Forms & Available Strengths:
Phenobarbitone Tablets: 30 mg, 60 mg; Paediatric Syrup: 20 mg/5 mL; IV/IM Injection: 200 mg/mL. Clobazam Scored Tablets: 5 mg, 10 mg, 20 mg.
Routes: Oral / Parenteral / Topical as specified by formulation

3. Mechanism of Action & Pharmacodynamics

Phenobarbitone prolongs GABA-A chloride channel opening duration; Clobazam increases chloride channel opening frequency with reduced sedation vs 1,4-BZDs.

4. Therapeutic Indications & Evidence-Supported Uses

  • Neonatal seizures and refractory status epilepticus (Phenobarbitone)
  • GTCS and focal epilepsy (cost-effective primary-care maintenance)
  • Lennox–Gastaut syndrome and catamenial/adjunctive epilepsy (Clobazam)

🇮🇳 Jurisdiction & Indication Note: Indications and schedules reflect Indian compendial and regulatory records (CDSCO / Indian Pharmacopoeia & NFI / NLEM 2022). Where international reference labels (US FDA DailyMed / NCBI StatPearls) are cited for pharmacokinetic or mechanistic parameters, international approvals do not automatically imply CDSCO approval in India.

5. Educational Dosage Context, Formulations & Administration

Educational Dosing & Regimen Summary: Phenobarbitone: Adult 60–180 mg PO OD at bedtime; Paediatric 3–5 mg/kg/day; Status Epilepticus Load 15–20 mg/kg IV at <=100 mg/min. Clobazam: Adult 10–30 mg/day PO (bedtime or BD); Paediatric 0.5–1 mg/kg/day.

Administration & Meal Timing: With or without food; bedtime dosing minimises daytime drowsiness. | Once daily at bedtime (Phenobarbitone); Once daily at bedtime or BD (Clobazam).

6. Pharmacokinetics, Metabolism & Renal/Hepatic Adjustment

Absorption & Disposition:
Absorption, distribution, metabolism, and excretion follow class pharmacokinetic profile; verify patient renal/hepatic function.
Metabolism & Biotransformation:
Renal: Extend Phenobarbitone interval if eGFR &lt;10 mL/min. Hepatic: Contraindicated in marked hepatic encephalopathy; halve dose in Child-Pugh B.
Elimination & Renal Adjustment:
Renal: Extend Phenobarbitone interval if eGFR &lt;10 mL/min. Hepatic: Contraindicated in marked hepatic encephalopathy; halve dose in Child-Pugh B.
Hepatic Impairment Considerations:
Renal: Extend Phenobarbitone interval if eGFR &lt;10 mL/min. Hepatic: Contraindicated in marked hepatic encephalopathy; halve dose in Child-Pugh B.

7. Contraindications, Precautions & High-Risk Warnings

Contraindications & Red-Flag Precautions:
  • CONTRAINDICATED IN ACUTE INTERMITTENT PORPHYRIA & SEVERE RESPIRATORY DEPRESSION: Phenobarbitone induces hepatic ALA synthase (precipitates fatal porphyria crisis!). Causes paradoxical hyperactivity in children and cognitive/fall risk in elderly.

Key Clinical Precautions: Renal: Extend Phenobarbitone interval if eGFR &lt;10 mL/min. Hepatic: Contraindicated in marked hepatic encephalopathy; halve dose in Child-Pugh B.

8. Adverse Effects Profile

Common & Mechanism-Related Adverse Effects:
  • Sedation, lethargy, cognitive slowing, ataxia, paradoxical paediatric agitation, folate/Vitamin D deficiency (long-term Phenobarbitone).
  • Respiratory depression (especially IV Phenobarbitone after Lorazepam/Diazepam), SJS/TEN, DRESS syndrome, physical dependence, withdrawal status epilepticus.
Serious / Dose-Limiting Adverse Effects:
  • Monitor for severe hypersensitivity, organ toxicity, or dose-limiting adverse events.

9. Major Drug–Drug, Drug–Food & Drug–Herb Interactions

  • Phenobarbitone is a potent pan-inducer of CYP3A4/2C9/2C19/UGT (reduces levels of Warfarin, DOACs, OCPs, Valproate, Lamotrigine)
  • Valproate inhibits Phenobarbitone metabolism (increases sedation 40%)

10. Clinical Monitoring, Patient Counselling & Storage

Clinical & Laboratory Monitoring: Monitor clinical response, baseline renal/hepatic parameters, and relevant serum biomarkers.

Pharmacist Patient Counselling Points:

  • Patient Counselling Checklist: Verify Schedule H1 / NDPS psychotropic register details; never stop tablets suddenly; supplement Calcium/Vitamin D and Folic Acid during chronic therapy.
  • Meal & Clock Timing Instruction: With or without food; bedtime dosing minimises daytime drowsiness. (Once daily at bedtime (Phenobarbitone); Once daily at bedtime or BD (Clobazam).)
  • Missed Dose Protocol: Take as soon as remembered unless close to next scheduled dose; never double the dose.
  • Geriatric Dispensing Pearl: Schedule: Schedule H1 / NDPS Psychotropic | NLEM 2022: Yes | Compendia: NFI 7th Ed 2026 / NLEM 2022 / CDSCO

Storage, Stability & Dispensing Safeguards: Store below 25°C–30°C in original moisture- and light-resistant packaging out of reach of children. Available forms: Phenobarbitone Tablets: 30 mg, 60 mg; Paediatric Syrup: 20 mg/5 mL; IV/IM Injection: 200 mg/mL. Clobazam Scored Tablets: 5 mg, 10 mg, 20 mg.

11. Visual Pharmacology & Mechanism Diagram (svg-v339-01-adme-12-step-journey)

THE 12-STEP ORAL DRUG JOURNEY THROUGH THE HUMAN BODY (LADME) Note: IV bolus enters Step 6 directly (F = 100%); Sublingual & Transdermal routes bypass Step 4–5 Portal First-Pass Metabolism 1. Oral Administration • Tablet / Capsule swallowed • Gastric emptying to duodenum pH 1.5–3.5 (Stomach) 2. Disintegration & Dissolution • Tablet breaks into granules • API dissolves in GI fluid Noyes-Whitney Dissolution Rate 3. GI Epithelial Absorption • Crosses intestinal villi • Passive / Active / P-gp efflux Small Intestine (Large Surface Area) 4. Portal Circulation • Mesenteric veins → Portal vein • Delivers blood to liver sinusoids Pre-systemic Venous Conduit 5. First-Pass Metabolism • Gut & hepatic CYP450 extraction • High: GTN, Propranolol, Morphine Determines Bioavailability (F = f_a × (1-E_H)) 6. Systemic Circulation • Hepatic vein → IVC → Heart • Unbound vs Albumin-bound drug Only FREE drug is active 7–8. Tissue Distribution (Vd) • Capillary permeation to organs • Blood-Brain & Placental barriers Vd = Dose / C_0 (L or L/kg) 9. Target Site of Action • Receptors (GPCR, Ion channel) • Enzymes & Carrier Transporters Pharmacodynamic Effect (E_max, EC50) 10. Hepatic Biotransformation • Phase I (CYP450 Oxidation/Hydrolysis) • Phase II (Glucuronidation/Sulfation) Converts lipophilic drug → hydrophilic metabolite 11. Renal & Biliary Elimination • Nephron: Filtration + Secretion − Reabsorption • Biliary excretion & Enterohepatic recycling Total Clearance CL_tot = CL_renal + CL_hepatic 12. Excretion from the Body • Urine (Primary polar metabolite route) • Bile/Faeces, Expired Air, Sweat, Milk Elimination Half-Life t1/2 = (0.693 × Vd) / CL
svg-v339-01-adme-12-step-journey — 8.1 Complete 12-Step Journey of an Orally Administered Drug (ADME): Figure 8.1: The 12-step physiological journey of a typical orally administered solid dosage form through Liberation, Absorption, Distribution, Metabolism, and Excretion (LADME). Note: Parenteral (IV), sublingual, and inhalational routes bypass gastrointestinal absorption and/or hepatic first-pass metabolism.

12. Authoritative References, Regulatory Sources & Editorial Disclaimer

Primary Compendial & Guideline Reference: Indian Pharmacist Desk Reference — Professional Edition 2.7 (2026–27) • Ch 11 [11.14] (p. 146)

Official Verification Portals: Indian Pharmacopoeia Commission (IPC) & National Formulary of India (NFI) • Central Drugs Standard Control Organization (CDSCO) • Ministry of Health & Family Welfare — NLEM 2022 • NCBI Bookshelf / StatPearls Pharmacology Reference • DailyMed (US FDA Official Prescribing Reference)

Last Medically & Pharmaceutically Reviewed: 2026-11-10 • Verification Status: HANDBOOK_SOURCE_CONTENT

Educational & Clinical Disclaimer: This reference profile is published solely for pharmacy education, academic study, and professional clinical reference. It does not substitute for patient-specific clinical judgement, qualified specialist oncology/medical supervision, or official CDSCO/IP prescribing information. Never self-medicate with prescription, Schedule H/H1/X, NDPS, or oncology medicines.

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Educational Reference Notice: This printout from THE INDIAN PHARMACIST (https://theindianpharmacist.com/medicine/11-14-phenobarbitone-phenobarbital-clobazam/, Last Reviewed: 2026-11-10) is an educational reference sheet for students and healthcare learners. It is NOT an official prescribing guideline or patient-specific treatment order.